Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
A borehole radar device is a subsurface detection tool that can be used for imaging geological targets in resistive formations, e.g., the delineation of orebody geometry, ideally using routinely drilled cover and exploration boreholes. Such radar device may be used in performing radar measurements of fractures or faults in geological targets under the ground, using electromagnetic waves having certain frequency bandwidth, e.g., frequencies of 10 MHz to several hundred MHz. This type of measurement typically requires supplying electric power to antennas in boreholes for transmitting and detecting radar signals and for transmitting the detected radar signals to an analysis device installed on the ground.
In one example, a borehole radar device can be equipped with a battery that is operable as a power supply, where the battery can be recharged at certain intervals. Recharging the battery may require pulling the radar device out of a borehole under the ground in order to access the battery for recharging, and reinstalling the radar device into the borehole after completing the recharging of the battery. Also, due to the limited charge duration of the battery, it may be difficult for the radar device to perform continuous radar measurement operation.
In another example, electric power may be supplied from an external power source to a borehole radar device through a power supply cable, e.g., made of a metallic cylindrical conductor. In this case, electromagnetic waves generated by a transmitting antenna of the radar device may be used to induce a current flowing through the power supply cable, which causes scattering of the electromagnetic waves. This scattering causes electrical coupling between the power supply cable and the antenna. Also, the scattered electromagnetic waves generated by the power supply cable may be received by a receiving antenna, which can be installed in another borehole for detecting radar measurement signals, and interfere with the detection of radar measurement signals by the receiving antenna.